How to Assemble A 48V Battery Pack with 18650 Lithium Battery?
1. Data calculation
First, we need to learn about two things:
① The size of the product that needs to be placed in the lithium battery pack and the required load capacity.
② The capacity required by the product – the capacity of the lithium battery pack that needs to be assembled.
Next, calculate the number of lithium batteries required to assemble a 48V20Ah battery pack step by step according to the formula.
Step 1 Calculate the number of series connection
Number of battery cells in series (S) = total voltage of the battery pack (V) ÷ rated voltage (V)
Therefore, the number of cells connected in series in a 48V20Ah battery pack is:
48V ÷ 3.7V = 13S, that is, 13 groups connected in series.
*Note: 2000mAh = 2AH
Step 2 Calculate the number of parallel connections
Number of battery cells in parallel (P) = total capacity of the battery pack (AH) ÷ rated capacity (AH)
It is concluded that the number of cells connected in parallel in the 48V20Ah battery pack is: 20AH ÷ 2AH = 10P, that is, 10 groups in parallel.
Step 3 Calculate the total number of batteries required
The total number of cells required for the battery pack = the number of cells connected in parallel (P) × the number of cells connected in series (S)
It is obtained that the total number of batteries required for a 48V20Ah battery pack is:
13S × 10P = 130
That is to say, 130 cells are needed to form such a battery pack.
2. Materials preparation
Choose the quality lithium batteries. It is best to buy the lithium batteries with guaranteed quality in a specialty store or from a reliable lithium battery manufacturer. Do not choose second-hand batteries of uneven quality. And if any problems occur in the assembly process, the lithium battery may have safety problems.
3. The specific steps of battery pack assembly
(1) Battery detection
Detect the capacity, rate, number of cycles of lithium batteries, and whether it meets the requirements of use. The equipment required for testing is a capacity detector.
(2) Cell pairing
The previous step preliminarily screened the batteries. Then the next step is to pair the cells to maintain the consistency of the internal resistance and voltage of the battery. A lithium battery sorting machine can be used.
Lithium battery sorting machine is a testing and sorting equipment for internal resistance, voltage and other parameters of cylindrical batteries. The sorting of the equipment is precisely controlled by servo motors. The testing organization adopts the five-position scanning test method, which can test multiple batteries at the same time. This greatly improves the stability of the test data. The operating system can generally query and count historical detection data for easy traceability. For example: 6-channel battery automatic sorting machine, 10-channel battery automatic sorting machine, 20-channel battery automatic sorting machine, 18650/21700 universal battery sorting machine, etc.
(3) Lithium battery with highland barley paper
The automatic highland barley paper pasting machine can also be used here.
Why paste highland barley paper on lithium batteries?
In fact, the use of highland barley paper in electronic products is very important. Pasting highland barley paper on the positive pole of the battery can prevent the positive pole from colliding with the positive pole, resulting in a short circuit or dust entering the gap. Highland barley paper has good insulation, water resistance and abrasion resistance.
(4) Lithium battery spot welding
After the cells are neatly arranged and fixed, the nickel strips can be used for the series connection.
The lithium battery spot welding machine can assemble a single battery cell into a battery pack by spot welding nickel sheets. After completing the series connection of lithium batteries, only the finishing work remains. Use adhesive tape to tie up the battery, and cover the positive and negative poles with barley paper to avoid short circuits caused by subsequent operation errors.
The installation of the protection board is also important. It is necessary to determine the position of the protection board, sort out the cables of the protection board, and use tape to separate the crossed parts of the cables to avoid the risk of short circuit. After the wires are sorted, they need to be trimmed, and finally the wires must be tinned. The solder wire must be of good quality.
(5) Finished product aging test
The finished battery pack needs to be tested before use.
The above is the assembly process of the 48V lithium battery pack. Hope it can help.